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378                           ZTRESH- WATER DOLPHINS                           CHAP,

The genus consists of some eight widely distributed species,
which are none of them, large Dolphins.

I^enorhynchsus has the following assemblage of characters :  -
Head wifeh. short, nofc very distinct beak. Dorsal and pectoral
fins falcate. Teeth small, twenty- two to forty- five in each half
jaw. Vertebrae ranging in number from seventy-three to ninety-
two. Eterygoid "boaes either in contact or separate. There are
fifteen or sixteen pairs of ribs, of which six are two-headed.
Of this genus Mr. True allows eight species, which have been
Increased by a ninth since the publication of his " [Revision." 1

Two species of LagenorJiynchus are known from our coasts ;
the rest are mainly southern in range. The British species are,
firstly, L, dlbirostris, a Dolphin of some 9 feet in length. It has
a large number of vertebrae, ninety-two in number. L, alMrostris
is a rare species, the first record of its occurrence on these shores
being in 1834. Since that date some eighteen individuals have
been shot or stranded on the shores of the [British Isles. The
second British species, 2J. c&utus, differs in colour from the first.
As in the last, the upper parts are black and the under parts
white; but in L. acutiis there is also a stripe on the flanks,
brownish in colour. It has fewer vertebrae, not more than
eighty-two.

The next genus of Dolphins, Sotalia, is characterised by 
Teefch tolerably large, twenty-six to thirty-five. The vertebral
formula is C 7,D 11 or 12, L 10 to 14, Ca 22. The pterygoids
are not in contact in the middle line. It has a distinct beak,

Of this genus there are some six species (the exact number, as
in so many other genera, cannot be positively asserted), most of
which are fluviatile or estuarine in habit. They are also on the
whole characterised by their pale, if not actually white, coloration.
S. sinensis of the Amoy is white with pinkish fins. Sotcdia
guianensis is American as its name denotes. It is figured by van
Beneden as of a pale brown colour. It is very abundant in the
Bay of Bio de Janeiro, and has the reputation of being a friend of
man like some other Dolphins. The natives hold that it will bring
to shore the bodies of drowned persons. The most singular species
of the genus is that recently described by Professor Ktikenthal
as $. t&m^ii?" This animal is purely fresh-water, being found in

. U.S. Nat. Mus. STo. 36, 1889.
* ZooL Jakrb. $&st. TheU, vi. 18^2, p.. 442.